textproduct: Albany

SYNOPSIS

High pressure will remain across the region today through Friday, bringing chilly temperatures along with dry weather. Milder temperatures return this weekend, along with increasing chances for precipitation for Saturday into early next week, some of which could start as some freezing rain.

NEAR TERM /UNTIL 6 PM THIS EVENING/

Key Messages:

- Below normal temperatures today despite sunshine for most areas.

- Uncertainty in cloud coverage for SW Adirondacks/western Mohawk Valley today.

As of 350 AM EST, low clouds have expanded southward into the Lake George/Saratoga region and upper Hudson Valley, and may extend into the Capital Region and eastern Mohawk Valley by sunrise. Other low clouds have expanded across northern Herkimer/NW Hamilton Counties, and may expand slightly farther south/east through sunrise. Temps have dropped to near/below zero across northern areas where skies have remained clear, with most other areas in the single digits to around 10 above.

The low clouds across the upper Hudson Valley and Capital Region may linger through mid morning before eroding, with mostly sunny skies expected through this afternoon. Somewhat more uncertainty on cloud coverage across the SW Adirondacks and western Mohawk Valley, as latest RAP13 and HRRR suggest current low clouds may hang tough, and could even expand farther south/east later this afternoon.

With forecast soundings suggesting a strong low level inversion remaining in place, the feeble late December sunshine may limit warming potential within valley areas, which may only reach the mid/upper 20s to perhaps around 30, while some higher terrain areas may reach into the 30s, above or closer to the strong inversion.

SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/

Key Messages:

- Spotty light freezing rain chances (30-50%) increase for late Friday night into Saturday with icy ground surfaces possible.

- Uncertainty regarding cloud coverage and low temperatures for tonight for areas mainly west of the Hudson River.

Challenging forecast for tonight regarding cloud coverage, as latest RAP13 and HRRR suggest low clouds may redevelop and/or expand east from central NY and may reach much of the SW Adirondacks, Mohawk Valley and eastern Catskills overnight, if not even farther east. As such, have not deviated quite as much from NBM min temps in these areas, with single digits/teens expected. Colder temps farther east, with single digits expected, and can not rule out some mins approaching zero.

For Friday, in addition to areas of low clouds for areas mainly north of I-90, some high clouds will begin increasing from the southwest. Temps will still be chilly, with upper 20s to lower/mid 30s in valleys, and mid/upper 30s across higher elevations.

Shortwave disturbance will track toward the region late Friday night into Saturday, along with increasing mid level warm advection. Model trends have been to increase chances (30-50%) for at least some spotty light precipitation to develop toward daybreak Saturday across the SE Catskills and mid Hudson Valley region, and then farther north and east into the Capital Region, Mohawk Valley and Berkshires/southern VT by mid to late Saturday morning. Although precipitation should remain light and spotty, surface temps will likely remain below freezing in most areas, and with significant warming aloft, P-type would most likely be freezing rain, at least to start. This could lead to icy ground surfaces Saturday morning, and in some cases, lingering into the afternoon hours. If this potential increases, Winter Weather Advisories will need to be issued later in time. Late day high temperatures should reach the lower/mid 30s across northern areas, and mid/upper 30s for areas south of I-90. However, despite temps warming above freezing, ground surfaces may remain colder and if left untreated, could allow icing to persist from any prior freezing rain.

For Saturday night, additional light precipitation is expected to overspread the region from the southwest. Some northern areas may remain near the freezing mark, allowing for additional freezing rain, with better chances for plain rain for areas south of I-90. Temps may rise through the night from initially being near/slightly below freezing for areas north of I-90.

LONG TERM /SUNDAY THROUGH WEDNESDAY/

Key Messages (Sunday through Monday):

- A prolonged period of regionwide rainfall is expected Sunday through Monday.

- Accumulations will likely reach 0.5" regionwide with a 50% to 80% chance of widespread accumulations of 1". Additionally, confidence is increasing in accumulations reaching 2" in portions of the Eastern Catskills (40% to 60% chance), Mid- Hudson Valley (20% to 40% chance), and western New England (20% to 40% chance).

- Antecedent frozen ground conditions and a pre-existing snowpack will increase the likelihood of river rises and localized flooding due to runoff and snowmelt.

By the inception of the long term forecast period Sunday morning, the axis of a large-scale,vertically stacked, negatively-tilted trough will become situated across the Southeast CONUS with multiple areas of low pressure developing beneath it at the surface along a warm front. Deep, anomalously rapid southwesterly flow (v-wind component +1.4 to +2 STDEV) about the leading flank of the trough will create a potent moisture fetch (IVT +1.5 to +1.8 STDEV)off the Gulf of Mexico, driving PWATs to rise to +2.5 STDEV above normal across the region. Increasing cyclonic vorticity intersecting the favored right entrance region of the upper jet streak situated over or just to our west, upward vertical motion will increase across eastern New York and western New England leading to the development of an area of steady rain that will stream in from the south and west by Sunday morning. Some timing discrepancies exist within latest solutions, but general consensus points to an onset time early to mid Sunday morning. Steady rain will continue throughout the day Sunday, becoming moderate to heavy at times especially in upslope regions of the Eastern Catskills and Southwest Adirondacks.

While confidence is relatively high in the aforementioned solution for Sunday, it decreases in reference to conditions for Sunday night through Monday. There are significant differences in the medium- range guidance in the depiction of the behavior of the area of low pressure that will form from the joining of the once multiple surface lows in the Southeast. While the CMCNH and ECMWF are similar in their portrayal of the low driving north and east into the Ohio Valley and Mid-Atlantic States, the progressive nature of the upper- trough as depicted in the CMCNH ensures that the surface low stays just south of our region, tracking into Coastal New England by early Monday afternoon. However, the slower solution of the ECMWF allows the low to track father west, sliding just off to our west. The differences in these solutions paints a significantly different picture in terms of the resultant QPF with the ECMWF accumulating much more rainfall than the CMCNH. Despite their differences, however, both have bullseyes of higher totals in the upslope regions of the Eastern Catskills and Southwest Adirondacks. The GFS on the other hand, is more of the middle ground between the other two in terms of the resultant QPF with it's depiction tacking the low much farther west of our area. The QPF realized from this event is going to be highly dependent on the track of the surface low as this will not only impact the axis of stronger forcing, but the duration of rainfall itself. The solutions depicted by the GFS and ECMWF would mean a more prolonged period of steady rainfall Sunday through Monday while that of the CMCNH would allow for stratiform rain to break up Monday such that precipitation becomes more showery in nature.

We will continue to monitor this system closely over the coming days as a solution wherein heavier QPF is realized could pose flooding concerns. Antecedent frozen ground conditions will increase runoff and while the pre-existing snowpack across much of the region is fairly dry, it could also add to the water running into low-lying/ poor drainage areas and rivers. At present, no matter the solution, there is an expectation for there to be periods of moderate to heavy rain across the region, especially in the Eastern Catskills. This could lead to poor drainage/urban area flooding and possibly isolated instances of flash flooding.

This system moves out of our reach by Tuesday morning, yielding shortwave ridging building into the region and a reinforcement of dry conditions for a brief time before another system looks to bring a potential mix of rain and snow Wednesday. However, the details of this system are fairly uncertain at this lead time so will provide additional details with further updates.

AVIATION /09Z THURSDAY THROUGH MONDAY/

Through 06z Friday...VFR conditions prevail across all terminals this morning with mainly clear skies across all of eastern New York and western New England. Infrared satellite imagery shows some low stratus protruding southward from Lake Champlain which, based on latest guidance and satellite trends, could make it into Glens Falls within the next hour or so. This would likely allow an MVFR ceiling to form, so this possibility was added to the GFL TAF. Guidance also indicates the possibility of mist/freezing fog fog forming at GFL between 09z and 11z so included a TEMPO to account for IFR visibility as a result of this. ALB and PSF could see some BCFG form later this morning, between 09z to 12z, but confidence is not high in this element of the forecast. So, included TEMPOs but maintained VFR conditions. Will continue to assess obs and trends overnight and make adjustments where necessary. Any mist/freezing fog will burn off quickly after sunrise tomorrow with clear skies remaining over the terminals, allowing conditions to return to or maintain VFR conditions in the case of POU. VFR conditions will then prevail throughout the 06z TAF cycle with variable winds sustaining speeds below 5 kt.

Outlook...

Friday Night: No Operational Impact. NO SIG WX. Saturday: Moderate Operational Impact. Chance of RA...FZRA. Saturday Night: Moderate Operational Impact. Chance of RA. Sunday: High Operational Impact. Definite SHRA...RA. Sunday Night: High Operational Impact. Definite RA. Monday: High Operational Impact. Likely RA.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...None. MA...None. VT...None.